What is ocean sound?

Ocean sound refers to the collection of acoustic energy present in marine environments, encompassing a variety of sources, including sounds from marine animals, geophysical noise from waves, wind, rain, and human generated noise from shipping, sonar, and offshore construction. This collection of sound at a given place and time is often call a soundscape. Monitoring ocean soundscapes provides key insight to understanding ecosystem dynamics, detecting environmental changes, and managing the impacts of noise pollution on marine organisms. Learn more at Discovery of Sound in the Sea

Why do we care? Ocean sound is critical for the survival of many marine animals because it is a primary means of communication, orientation and navigation, finding food, avoiding predators, and choosing mates. As such, human activities that produce underwater sounds have the potential to negatively impact animals by reducing their ability to hear prey, predators, and each other. National marine sanctuaries are home to many acoustically active marine animals and understanding the presence and impacts of noise is a conservation priority. Further, the occurrence and types of sounds present offer key insights on animal presence, species behaviors, human-use patterns, and changing ocean conditions.

When, where, and why are we listening?

NOAA’s Office of National Marine Sanctuaries maintains a nationally coordinated underwater sound monitoring network across the National Marine Sanctuary System, known as ONMS Sound. ONMS works with partners to monitor sound within national marine sanctuaries. Ocean Sound monitoring sites are located in strategic locations within sanctuary boundaries and record continuously. Audio recordings and standardized sound measurements are available through the NOAA National Centers for Environmental Information’s Passive Acoustic Archive. Explore the monitoring sites here.

The Cordell Bank National Marine Sanctuary (CBNMS) is entirely offshore. Within its 1,286 square miles, the sanctuary protects soft seafloor habitat, a rocky bank, deep sea canyons, and communities of wildlife throughout. Its surface waters are feeding areas for local and migratory seabirds and marine mammals.

Ocean sound monitoring in this sanctuary began in 2014, as part of the Ocean Noise Reference Station. This unique network of hydrophones is a collaborative effort between Pacific Marine Environmental Laboratory, all NMFS Science Centers, the NOS National Marine Sanctuary System, and the National Park Service to establish and collect consistent and comparable long-term acoustic data sets covering all major regions of the U.S. The primary objective of the this network is to monitoring trends in Ocean Noise, a critical aspect of NOAA’s mandate for ocean and coastal stewardship.

Site Primary.monitoring.purpose Oceanographic.Setting Seasonality Vessel.Traffic.Setting Latitude Longitude Region Sanctuary TotalDays StartDate Learn.more..website
NRS11 To continue long-history of monitoring trends in ocean noise, including cetacean species presense and vessel movement Continental slope (>200m), exposed to deep-water Seasonal patterns driven by known sounds from baleen whales Constant large vessel activity - in traffic fan approaching San Fran/Oakland 37.88082 -123.4353 West Coast CB 1433 2015-10-17 https://soundcoop.portal.axds.co/#soundcoop/datasets/NRS11

Summary of Monitoring Effort

What sounds contribute to the soundscape?

A visualization of ocean sound in offshore habitat. Seasonal summary of measured sound levels (colored lines) shown as median hourly values over all available data. Vertical lines indicate representative frequencies for different sound sources: ship noise (63, 125 Hz), fin whales (20 Hz), blue whales (45 Hz), and humpback whales (500 Hz). The bottom bar shows how the data are distributed in the different wind categories: low < 5 m/s, med 5-10 m/s, high >10 m/s. Dotted lines are modeled wind noise at this depth based on Hildebrand et al 2021.
A visualization of ocean sound in offshore habitat. Seasonal summary of measured sound levels (colored lines) shown as median hourly values over all available data. Vertical lines indicate representative frequencies for different sound sources: ship noise (63, 125 Hz), fin whales (20 Hz), blue whales (45 Hz), and humpback whales (500 Hz). The bottom bar shows how the data are distributed in the different wind categories: low < 5 m/s, med 5-10 m/s, high >10 m/s. Dotted lines are modeled wind noise at this depth based on Hildebrand et al 2021.

The median power spectral densities (PSD) for all hours across all years are calculated from calibrated audio data using community software tools: Triton Soundscape Metrics, MANTA, or PyPAM. Triton software calculates the one-third octave band sound pressure levels by integration of PSD levels with a 1 Hz/1 second resolution and a median was used to calculate hourly values over no less than 1,800 1-s values for that hour and converted to decibels (dB re 1 μPa). MANTA and PYPAM software calculates power spectral density (PSD) levels per minute (μPa²) within the hybrid milledecade frequency bands. PAMscapes was used to calculate the median for each hour within one-third octave bands. These values were then converted to 1-Hz resolution to match the wind model results by converting to pressure and dividing by the band width before converting back to sound spectrum levels in decibels (dB re 1 μPa/Hz).

Figure 1: Caption for Image 1

Figure 2: Caption for Image 2